Systems for moving objects (e.g., sliding vehicle doors, lift gates, trunks, windows, and the like) often incorporate a pinch detection system that detects when a obstacle is in the path of the moving object. Currently known systems compare the motor force or torque with a reference force or torque and determines that a pinch condition exists if the actual force is greater than the reference force by a certain amount.
The reference force used to detect the pinch condition is normally obtained from a reference field that ideally represents the force profile of the moving object. Customizing the force profile for each individual object is time-consuming and costly, so some current systems use a pre-determined reference field that is obtained from a theoretical design value or a pre-calculated average of force profiles from several samples. Even with these calculations, manufacturing variances from object to object will create inevitable errors between the predetermined reference field and the actual force profile of the object. These variations require the pinch detection threshold to be increased to avoid false detection of pinch conditions, but increasing the pinch threshold undesirably increases the pinching force as well. Further, if the reference field collapses or is unavailable for any reason, pinch detection in current systems is rendered impossible.
There is desire for a system that can adapt to different force profiles to optimize pinch detection for a given moving object without obtaining force profiles of each sample. There is also a desire for a system that can keep pinching force constant regardless of the pinch detection threshold value.